FrankChen021 opened a new pull request, #20272:
URL: https://github.com/apache/druid/pull/20272
### Description
The Docker startup scripts use `echo -e` when writing runtime properties. The
behavior of `echo -e` is not portable across `/bin/sh` implementations.
On Ubuntu-based Docker images, `/bin/sh` commonly resolves to `dash`, which
does
not recognize `-e` as an option. As a result, the generated runtime
properties
can contain a spurious `-e` property with an empty value. This property is
then
visible through `sys.server_properties`.
#### Shell behavior
For:
```sh
key=foo
value=bar
echo -e "\n$key=$value"
```
The output differs by shell:
| `/bin/sh` implementation | Output |
| --- | --- |
| Bash | A leading newline, followed by `foo=bar` |
| BusyBox `ash` | A leading newline, followed by `foo=bar` |
| Ubuntu `dash` | `-e`, followed by a newline and `foo=bar` |
The `dash` output is effectively:
```text
-e
foo=bar
```
Java's properties parser interprets the first line as a property named `-e`
with an empty value.
Because the scripts use `#!/bin/sh`, behavior is determined by the image's
`/bin/sh` implementation. This was reproduced with the Ubuntu-based Docker
images used by the `spdi-27` and `spdi-37` branches. The current master image
uses BusyBox, which masks the issue because its `echo` supports `-e`.
#### Observed symptom
The following screenshot shows the unexpected `-e` row returned by
`sys.server_properties`:
<!-- SCREENSHOT_ATTACHMENT -->
#### Changes
Replace the non-portable `echo -e` calls in both `druid.sh` and `peon.sh`
with
POSIX-compatible `printf`:
```sh
printf '\n%s=%s\n' "$key" "$value"
```
The existing property destination and key/value behavior are unchanged.
`sys.server_properties` does not require any code changes.
#### Verification
- Built the Docker image before and after the change.
- Reproduced the issue under `dash`: `/status/properties` contained
`"-e": ""`, and `sys.server_properties` returned the corresponding row.
- Verified after the change that `-e` was absent while normal properties were
still present.
- Ran `sh -n distribution/docker/druid.sh`.
- Ran `sh -n distribution/docker/peon.sh`.
- Ran `git diff --check`.
##### Key changed files
- `distribution/docker/druid.sh`
- `distribution/docker/peon.sh`
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